20
May

White Spot Syndrome

Aetiology
Classification of the Causative Agent

White spot virus (WSV) or white spot syndrome virus (WSSV) is a presently unclassified rod-shaped to obovate, enveloped double-stranded DNA virus with a single filamentous appendage. The cellular location is nuclear and the genome is large at approximately 290 kbp.

Resistance to Physical and Chemical Action

Temperature:   Inactivated at 50C/20 minutes, 70C for 5 minutes, drying at 30C.
pH:   Inactivated by pH 1 for 10 minutes, pH 3 for 1 hour, pH 12 for 10 minutes at 25C.
Chemicals:   Inactivated by 15% NaCl 28C for 24 hours, 0.5 g/ml residual ozone for 10 minutes at room temperature, oxidising reagents and ethyl ether.
Disinfectants:   Inactivated by sodium hypochlorite and povidone iodine at 100 ppm for 10 minutes and 10 ppm for 30 minutes, benzalkonium chloride 75 ppm for 10 minutes.
Ultraviolet:   Inactivated by 9 105 w s/cm2 for 60 minutes.
Survival:   At low concentration, remains viable in sterile sea water 5 days at 28C, longer at lower temperatures. Viable in water from outbreak ponds approximately 4 days at 25-28C.

Epidemiology
Hosts

  • WSV is highly infectious for most known species of cultivated penaeid shrimp.
  • Natural infections have been recorded from black tiger shrimp (Penaeus monodon), Kuruma shrimp (P. japonicus), Chinese white shrimp (P. chinensis), banana prawns (P. merguiensis and P. inducus), white shrimp (P. vannamei) and other penaeids.
  • Until proven otherwise, it is reasonable to assume that all cultured penaeids would be susceptible to infection.
  • Natural infections also occur in many species of decapods (crabs, crayfish, lobsters and shrimp) or other crustaceans, although often not lethal.

Transmission

  • Horizontal transmission may be direct or vectorial, water being the major abiotic vector.
  • Rapid transmission occurs from infected shrimp through the water and by cannibalism of weak or moribund shrimp.
  • Animate vectors include over 40 known species of crustaceans.
  • The major source of infection for rearing ponds is grossly healthy carrier fry that have acquired the virus from spawners in shrimp hatcheries.
  • Transovarial transmission has been confirmed and intra-ovum transmission has not been ruled out. However, if it exists, its frequency is very low.

Sources of Virus

  • The mode of virus shedding from infected shrimp has not been established, but cohabitants with infected carriers acquire active infections within 36-48 hours.
  • Infected transport water, intake water, nets and other equipment.

Occurrence

White spot disease (WSD) has been recorded from most Asian countries were penaeid shrimp are pond reared. Original outbreaks were reported from the People’s Republic of China in 1993 and they spread rapidly thereafter to Japan, Taipei China and the rest of Asia, but not Australia. Since early 1999, it has been widely reported from shrimp farms in the southern United States of America, Central America and northern South America. Disease outbreaks may occur at all seasons and at all phases of pond rearing, but they seem to be favoured by widely fluctuating environmental conditions. Other precipitating factors may include stress induced by chemical and insecticide residues.

For detailed information on occurrence, see recent issues of World Animal Health and the OIE Web site.

Diagnosis

Gross Signs

  • Decreased feed consumption or cessation of feeding and increased mortality in the population.
  • Lethargic or moribund shrimp accumulate at the pond surface and edges with slow to erratic swimming behaviour.
  • Overall body colour often reddish.
  • Minute to large (several mm diameter) white inclusions embedded in the cuticle, especially in the removed carapace held to the light after scraping off attached tissue (not always seen).

Lesions

  • There are no pathognomonic gross lesions.
  • White inclusions in the cuticle are not always seen, especially in very acute infections. In some cases they may be very small and difficult to resolve.
  • Red body coloration not always seen.
  • Histopathology a minimum requirement for diagnostic confirmation.

Differential Diagnosis

  • High alkalinity may sometimes induce formation of calcium deposits in the cuticle in the absence of WSD.
  • Poor water quality in rearing ponds (high ammonia, low oxygen, high and low pH).

Laboratory Diagnosis
Procedures

Confirmation of the agent

  • Histopathology by haematoxylin-eosin (H&E)-stained sections shows moderate to large numbers of hypertrophied nuclei with basophilic central inclusions surrounded by marginated chromatin in tissues of ectodermal and mesodermal origin (particularly subcuticular tissues of the stomach, cephalothorax and gills). Early-stage hypertrophied nuclei show Cowdry type-A inclusions.
  • Polymerase chain reaction (PCR) of tissues and haemolymph.
  • Western blot assay.
  • In situ DNA hybridisation.
  • Transmission electron microscopy.

Serological tests

  • None currently available.

Samples

Identification of the agent

  • Whole shrimp fixed for histopathological examination.
  • Haemolymph, gill tissue or pleopods homogenised in lysis buffer.

Disease Prevention and Management
Sanitary Prophlaxis

  • PCR Screening and elimination of infected broodstock from the hatchery.
  • Stocking of ponds with post larvae (PL) of known health status or screened as negative for WSSV by PCR.
  • Proper cleaning and disinfection of ponds before stocking, including removal of potential carrier crustaceans.

Elimination or screening of potential carriers from exchange water.

  • Avoidance of exchange of equipment amongst ponds.
  • Avoidance of the use of fresh aquatic feeds.
  • Continuous removal and destruction of moribund and dead shrimp whenever they appear.

In outbreaks

  • Strict isolation of outbreak ponds with movement controls and control of human traffic.
  • Destruction of all infected and exposed shrimp by incineration or burial.
  • Thorough cleaning and disinfection of outbreak ponds.

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20
May

All About Shrimp

All Shrimp Are Not The Same:

Each type or species of shrimp have their own characteristics with flavor, texture, cooking times, and a best cooking method for them. You have Gulf Shrimp, Farm Raised Shrimp, Tiger Shrimp, Imported Shrimp, and Coldwater Shrimp. In fact, there are over 300 species of shrimp in the world.

The flavor and texture of each type of shrimp are influenced by the waters they come from or are raised in, plus from what they eat or are fed. Wild shrimp feed on seaweed and crustaceans which gives them a more enriched flavor and thicker shells. The ability to swim freely also makes the meat firmer.

Shrimp are found abundantly in America, off the Atlantic and Pacific seaboards in inshore waters, wherever the bottom is sandy. Shrimp are in season from May to October and 95% of the shrimp caught come from the warm waters of the South Atlantic and Gulf states.


Buying Shrimp:

Fresh shrimp is highly perishable! Fresh shrimp should ideally be eaten within 24 hours of purchase. Unless you live in the part of the country where you can actually buy “fresh” shrimp, it is best to buy frozen shrimp. Most shrimp in the grocery stores are frozen shrimp that has been thawed. The shelf like of thawed shrimp is only a couple of days, whereas shrimp stored in the freezer retain their quality for several weeks. Fresh Shrimp: Avoid shrimp that smells of anything other than salt water. If there is any hint of the aroma of ammonia, it’s a sign the shrimp is way past its prime. Truly fresh shrimp will have almost translucent flesh. Do not buy shrimp with black spots or rings (unless it’s black tiger shrimp) as this indicates the meat is starting to break down. Also avoid pink meat.Frozen Shrimp: If possible, AVOID shrimp that has been peeled and deveined before freezing. It can cause a loss of flavor and texture (shells will help to protect the meat of the shrimp and add more flavor to it).
 

1 pound of raw shrimp in their shells = about 1/2 pound peeled and cooked shrimp


Shrimp Sizes:In the United States, shrimp are sold by count. This is a rating of the size and weight of the shrimp. The count represents the number of shrimp in a pound for a given size category.

This shrimp sizing chart is to be used for buying frozen or fresh Shrimp in the shell without the head on. All shrimp are sold by sizes, whether they are sold by the actual count or by a name such as jumbo or extra large. Shrimp will be labeled both ways to help you determine the size you are buying. For example a Jumbo Shrimp would have 21 to 25 shrimp per pound. NOTE: The U in the first three Shrimp sizes stands for under that many shrimp in a pound. For example U/10 would be under 10 shrimp per pound.

Market/Trade Name Shrimp count (number)
per pound
Average shrimp per pound
Extra Colossal U10 5
Colossal U12 9
Colossal U15 14
Extra Jumbo 16/20 18
Jumbo 21/25 23
Extra Large 26/30 28
Large 31/35 33
Medium Large 36/40 38
Medium 41/50 45
Small 51/60 55
Extra Small 61/70 65

Defrosting Frozen Shrimp:

Never defrost any type of shellfish at room temperature and it is best not to defrost them in the microwave either. Defrost shrimp either in the refrigerator or in ice cold water. Do not defrost in a warm place or microwave.



shrimp deveinersDeveining Shrimp: (Photo on right is of different types of shrimp deveiners that can be purchased.)

Should shrimp be deveined? 

The black “vein” that runs along the back of the shrimp is actually its digestive tract. These veins are in fact edible but if eaten they can taste gritty and dirty, particularly with larger prawns or shrimp. While it isn’t necessary to remove the vein, some people say the shrimp look and taste better when deveined. This is pretty much a question of aesthetics. Most cooks won’t bother deveining medium-sized or smaller shrimp, unless they look particularly dirty. You can see the vein through the shell and meat, so use your own judgment.

Deveining shrimp: 

  • Shrimp cook well in or out of their shells, but they’re easier to devein before cooking.
  • Run the deveiner or the tip of a small knife down the back of the shrimp. This will allow you to remove the vein.
  • You may remove the shell at this time or boil with shell on and remove after cooking.
  • If frying, shell should be removed first.
  • You can devein shrimp while leaving the shell on (the shell adds flavor and can protect the meat if you’re grilling the shrimp.)


Cooking Shrimp:

Shrimp can be cooking in a variety of way. They can be boiled, steamed, grilled, sautéed, baked, or deep-fried. They can also be cooked with or without the shell, with the vein or deveined.

Shrimp should always be cooked quickly in order to preserve their sweet, delicate flavors. They are very quick to cook, and the flavor can easily be ruined by overcooking. Most shrimp cook in as little as 3 minutes – when they’re pink, they are done. Boiling Method:  This is probably the most common method of cooking shrimp, particularly the smaller types. To properly boil shrimp:

  • Place a pound of shrimp in a quart of rapidly boiling water with (3) three tablespoons of salt.
  • Reduce the heat, cover the pan, and return to a boil. Let simmer until the flesh has lost its glossy appearance and is opaque in center (cut to test).
  • Jumbo shrimp take about 7 to 8 minutes, large shrimp take about 5 to 7 minutes, and medium size are done in about 3 to 4 minutes.
  • If your shrimp are to be used in a recipe and not eaten right away after cooking (such as grilling), they should be plunged into cold water to stop the cooking process. (Do not let them cool in the cooking liquid. They will continue to cook and get tough)

Grilling Method: Grilling is a popular method for cooking larger shrimp. Smaller shrimp may also be grilled, but it is usually best to put them on skewers first.

  • Once the grill is hot place the larger shrimp or skewered smaller shrimp on the prepared grill, leaving room between each shrimp or skewer.
  • Brush the prawns with a little olive oil and then sprinkle them with salt, pepper, and garlic.
  • Grill for 3 to 4 minutes or until the prawns have turned pink, turning the shrimp and/or skewers once halfway through cooking time.
  • Remove from the heat and serve


Guidelines for Brining Raw Shrimp:

Brining is very easy and economical, and requires no special cookware. Brining is like a marinade as it keeps food moist and tender. Brining or salting is a way of increasing the moisture holding capacity of shrimp resulting in a moister product when it is cooked. Brining is a process to be used if you want to put a little more “snap” to shrimp. Brining draws extra moisture out of the shrimp flesh, thus firming it’s texture.  Brining turns potentially mushy shrimp into shrimp with a chewy texture similar to lobster tail.  Brining can be used with either peeled and deveined raw shrimp or shell on raw shrimpDo not brine raw shrimp if they are to be used for poaching and other wet cooking techniques. Tests and found that the brining lets the shrimp retain more moisture when cooked with a dry method (grilling or pan frying, for example). 

Kosher salt and table salt (without iodine) are the most common salts used in brining. Sea salt can be used, but it tends to be quite expensive. I usually use kosher salt. A cup of table salt and a cup of kosher salt are not equal. Table salt weighs approximately 10 ounces per cup and kosher salt weighs approximately 5 to 8 ounces per cup depending on the brand. If using kosher salt in a brine, you must use more than a cup to achieve the same “saltiness” you would get from a cup of table salt. The chart below shows how to substitute the two most popular brands of kosher salt for ordinary table salt when brining.

Table Salt (without iodine) – 1 cup
Diamond Crystal Kosher Salt – 2 cups
Morton Kosher Salt – 1 1/2 cups

How long to brine raw shrimp:

It is possible to end up with meat that’s too salty for your taste. To avoid this, brine on the low end of the time range on your first attempt. You can always brine longer next time, but there’s no way to salvage a piece of meat that’s been brined too long.

Shrimp (peeled)   -  20 to 30 minutes
Shrimp (unpeeled)  -   40 to 60 minutes

Brine for shrimp:
1/4 cup kosher or coarse salt
1/4 cup sugar
1 cup boiling water
2 cups ice
Stir salt and sugar into boiling water until dissolved; pour into large bowl filled with ice; add up to 2 pounds raw shrimp. Let sit in the brine, refrigerated for 20  to 60 minutes (see chart above). Remove shrimp from brine and drain thoroughly. Rinse the shrimp thoroughly under cold water and dry on paper towels. Refrigerate the raw brined shrimp until ready to use in your recipe.



Freezing Shrimp – (Raw or Cooked)

Select high-quality, fresh shrimp for freezing. Shrimp can be frozen cooked or raw, in or out of the shell. For maximum storage life and quality, freeze shrimp raw, with heads removed, but shells still on. Shrimp may also be frozen in water in a freezer container or wrap it well in plastic and place it in the coldest part of the freezer where it will keep for about one month.


Shrimp Etiquette:

Shrimp Cocktail:  If large shrimp are served in a stemmed glass, pick them up with an oyster fork or whatever fork is provided and bite off a mouthful at a time, dipping into the sauce before each bite. Large Shrimp:  If large shrimp are served on a platter with sauce and no fork, pick up with your fingers, dip into sauce and put to your mouth. When eating shrimp with the tail still on, hold the shrimp by the tail and dip it into the sauce once. Eat it in one bite if it is not too large. Otherwise, eat it in two bites. Do not dunk the second bite into the sauce! Then discard the tail as you would olive pits or toothpicks. Deep-Fried Shrimp:  Tail-on deep-fried shrimp is meant to be eaten with the fingers.Skewered Shrimp:  If eating shrimp on a skewer, slide the shrimp off onto a plate (even if it is a paper plate at a cook out). Skewered shrimp should never be eaten like a corn dog.

Oriental Dishes:  When eating shrimp with the tail  that are part of some orientail dishes or fried foods, remove the tail with a fork and set to the side of your plate or on a separate “discard dish” if one is provided.
 

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16
Dec

Konsep Program Budidaya Antara

Program Budidaya Antara (BDA ) telah disepakati Inti dan Plasma AWS.  Mulai berlaku 15 Februari 2008 lalu di Blok-Blok yang belum direvitalisasi. Program ini mengganti konsep budidaya Pra Intensif Lanjutan (PIL).  Apa saja kendalanya? Penulis akan mencoba memaparkan berdasarkan metode yang digunakan oleh sebuah perusahaan tambak terintegrasi vertikal terbesar di dunia, PT Central Proteinaprima (CP Prima-www.cpp.co.id) yang memiliki PT Aruna Wijaya Sakti, semacam bisnis unit pengolahan tambak yang dahulunya bernama PT Dipasena Citra Darmaja.

Istilah BDA menjadi topik hangat saat perundingan PKS Inti-Plasma PT Aruna Wijaya Sakti (AWS) mendekati finalisasi. Ini merupakan istilah baru, setelah sebelumnya ada konsep serupa berjudul Pra Intensif (PI) dan Pra Intensif Lanjutan (PIL).  Program Budidaya Antara (BDA) disepakati oleh Perusahaan AWS dan Petambak Plasma AWS di Tabek Indah, Natar-Lampung Selatan pada tanggal 1 Februrari 2008. Setelah menyempurnakan beberapa persiapan dan kelengkapannya, tebar pertama BDA baru dapat dimulai tanggal 1 Maret 2008. Program BDA dilakukan di blok-blok yang belum direvitalisasi seperti Blok 04, 05 dan Blok 08 sampai Blok 15. Sedangkan untuk Blok 6 memungkinkan pelaksanaan program BDA dengan mempertimbangkan waktu dan kondisi rehabilitasi.

Dengan lahirnya sistem BDA ini otomatis konsep PIL dihentikan. Dan secara umum bisa dimulainya program BDA jika telah memenuhi syarat-syarat antara lain : Telah selesainya dilakukan pendataan tambak yang siap melakukan BDA, pemberlakuan Kawasan Berikat, kesiapan logistik, kesiapan pengamanan, kesiapan Tim Aquaculture, kesiapan FPD alias Coldstorage, kesiapan Power Plant dan kesiapan Tim Verifikasi. Sedangkan secara khusus program BDA ini diperuntukkan bagi petambak plasma yang menunggu jadwal revitalisasi dengan kondisi tambak yang memungkinkan budidaya, tanpa perbaikan yang dilakukan oleh perusahaan  AWS / Inti.

Dalam program ini, pihak   perusahaan berkewajiban memberikan pinjaman kepada plasma yang ikut program BDA, berupa benur, pakan, energi listrik, obat-obatan dan pemberian pelayanan dan penyuluhan, dari mulai persiapan sampai panen. Dalam hal pelayanan jasa perbaikan pompa, perusahaan Inti belum dapat menyediakan. Namun, jika dalam operasional BDA terjadi kerusakan pompa dapat dibicarakan secara khusus antara LMPK dengan Perusahaan Inti. Kemudian ketika program BDA sampai masa panen, maka disepakati bersama bahwa hasil seluruhnya harus dijual ke perusahaan Inti dengan menggunakan mekanisme harga PIL.

Pengembalian Pinjaman

Sementara itu, pinjaman (Hutang Bulanan Plasma/HBP) tetap diberikan kepada petambak plasma yang melakukan BDA. Juga untuk petambak yang terkena program relokasi atau pekerjaan Module Based.

Dalam BDA, biaya listrik dan HBP dalam 1 siklus dipotongkan sebesar 50 % dari hasil panen, sedangkan biaya lainnya dipotong sebesar 100 %. Namun, jika ternyata tidak terlunasi dari hasil panen BDA ini  (dalam  1 Lot), maka akan ditambahkan ke hutang Pra-Intensif dan Pra-Intensif Lanjutan yang dikumulatifkan saat budidaya Intensif kelak.

Selain itu , ada   kriteria-kriteria lainnya, diantaranya :

  1. Dengan dimulainya BDA maka budidaya PIL diganti BDA.
  2. Bagi petambak yang tidak bisa melaksanakan BDA diberi kesempatan untuk bekerja selama revitalisasi, atau dapat memberdayakan Tambak R. \
  3. Bagi petambak yang saat dimulai BDA sedang melakukan budidaya PIL, maka konsep budidaya PIL diganti BDA, dimana biaya produksi dipinjami Inti dan semua hasil panen dijual kepada Perusahaan Inti.
  4. Bagi petambak plasma yang lokasinya akan segera direvitalisasi, maka budidaya PIL atau BDA akan dihentikan.
  5. Cut Off (penghentian pengihtungan biaya) Budidaya PIL terhitung sehari sebelum BDA diberlakukan, atau tepatnya tanggal 14 Februari 2008.
  6. Seluruh hutang yang ada pada budidaya PIL dibebankan pada Budidaya Intensif.

Sejak dimulai hingga bulan April 2008, program BDA berjalan dengan berbagai kendala. Namun secara garis besar dapat dikatakan lancar. Transaksinyapun sebagian masih manual, namun secara perlahan akan mulai diperbaiki dengan sistem intranet yang selalu on line. Saat ini kita sedang uji coba sistem online ini dengan Blok IV, blok yang lainnya nanti akan menyusul.

Reference: Majalah Aruna (majalah internal PT Aruna Wijaya Sakti)

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10
Dec

Pentingnya Manajemen Dasar Tambak

Dalam pengelolaan tambak banyak orang terpaku pada manajemen kualitas air namun sering melupakan manajemen dasar tambak. Padahal sebenarnya kondisi dasar tambak dan kontak antara dasar tambak dengan air sangat mempengaruhi kualitas air. Pasalnya di tambak perlu disadari bahwa limbah yang mengendap di dasar tambak, baik langsung maupun tidak langsung, akan mempengaruhi kualitas air tambak secara keseluruhan.

 

Pada akhirnya, kualitas air tambak ini akan mempengaruhi kondisi udang yang ada di tambak. Udang sendiri dikenal punya habitat di kolom air dan dasar tambak- terutama saat molting- jelas akan sangat mudah terpengaruh kesehatannya oleh kualitas dasar tambak dibandingkan kualitas air.

 

Mengapa dasar kolam sangatlah penting? Sebab semua limbah dan buangan sisa metabolisme akan mengendap di dasar tambak.  Contohnya adalah kotoran udang, sisa pakan, plankton mati, bangkai udang, dan sisa pupuk akan mengendap dan berakumulasi di dasar tambak. Lama kelamaan tumpukan ini akan terus meningkat seiring bertambahnya umur budidaya. Dampaknya adalah meningginya H2S dan NH3.

 

Bahan-bahan organik yang mengendap ini akan diurai oleh bakteri pengurai di dasar tambak. Hanya kualitas dasar tambak akan sangat tergantung saja kecepatan laju penguraian . Dan penguraian ini membutuhkan oksigen serta bakteri pengurai. Di sinilah dibutuhkan manajemen dasar tambak yang meliputi pengangkatan lumpur, pemberian bakteri dikomposer, pengeringan dasar kolam, pengapuran, dan penurunan proses euthophikasi. Tujuan manajemen dasar tambak ini adalah agar kondisi kolam tidak tereduksi.

(diolah dari Majalah Mitra Bahari No I/2008) *
*) Majalah internal PT Central Proteinaprima Tbk (www.cpp.co.id)

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10
Dec

Langkah Persiapan Tambak

Target yang akan dicapai dalam persiapan tambak adalah mendapatkan pH tanah 6,5,ORP >+400 mV dan tanah dasar tambak kering. Tambak dengan pH rendah biasanya nilai alkalinitas yang rendah sehingga dibutuhkan aplikasi kapur untuk menaikkan nilai pH . Jumlah kapur yang digunakan juga harus mengacu pada alkalinitas atau nilai pH tanah. Nilai pH yang paling ideal adalah 7 di mana ketersediaan Phospor paling optimal dan hamper semua bakteri pengurai mampu bekerja optimal di nilai pH ini.

Sedangkan tujuan dari pengeringan tmabak adalah untuk menurunkan kandungan air dalam tanah sehingga udara dapat masuk ke dalam pori-pori tanah.Udara yang masuk ini akan menambah suplai oksigen di dalam tanah dan meningkatkan dekomposisi aerobik dari bahan organik. Periode pengeringan tambak biasanya antara 2-3 minggu sehingga hampir semua sisa bahan organik yang tertinggal di dasar tambak  akan terdekomposisi.

 

Yang  tidak boleh dilupakan adalah pembuangan lumpur di kolam. Pembuangan ini harus dilakukan sebab lumpur akan terakumulasi di dasar tambak dan tdiak semua sedimen ini dapat dioksidasi lewat pengeringan atau dinetralkan dengan pengapuran.

 

Bagaimana jika tambaknya tidak bisa dikeringkan total? Solusinya adalah dengan melakukan disinfeksi dasar tambak untuk emmatikan pathogen yang berpotensi menjadi masalah. Disinfektan yang bisa dipakai adalah Chlorine 100 ppm dan KMnO 410 ppm.

 

(diolah dari Majalah Mitra Bahari No I/2008)*

 

*) Majalah internal PT Central Proteinaprima Tbk (www.cpp.co..id)

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05
Dec

SHRIMP INDUSTRY PROBLEMS

1. Land use system
The mapping of land use is a basic requirement for the development of an area. Control over areas which still do not have a land use map is often less than satisfactory. As a result conflicts in their usage between persons or companies are often encountered in such areas.

2. Master plan
In designing their tambak system, the parties concerned often do it individually without considering the rest of the area surrounding their own farm. This occurs because there is still no master plan which would regulate the number and the lay out of tambaks according to the capacity of the environment in terms of fresh and sea water, disposal of waste water and other ecological factors. The result is that existing tambak operations already exceed a particular area’s capacity so that they can no longer be managed or operated correctly, thus ending in not small losses.

3. Water supply
The management of salinity during the grow-out period is very important in ensuring the health and growth of the shrimps. The traditional tambaks generally have great difficulty in managing their salinity because their water canals are not satisfactory and are almost not maintained at all.

In order to overcome this problem, the rehabilitation and repair of canals is needed. Aside from this, the drilling of wells to draw ground water, whether fresh or brackish, especially during the dry season when the salinity rises or during the wet season when the salinity is too low, can help solve this problem. However there is also a need to properly manage the drilling of wells for fresh water in these areas due to the possibility of saltwater intrusion inland.

4. Working capital
On the part of the small farmers, working capital is a limiting factor even if they operate their tambaks using only extensive or traditional methods. Credit such as that available under INTAM has certain requirements which appears to be still beyond the reach of farmers so that the realization rate of INTAM Kredit is relatively low resulting in the stagnation of its execution. A Special INTAM programme (OPSUS) was implemented according to the Letter of Instruction No. 1 of the Regent of Gresik, dated 25 February 1988, in the Village of Ujung Pangkah Wetan, Ujung Pangkah Subdistrict, covering 152 ha. Up to this time, there is still a need to continuously develop and manage the area so that the expected harvest can be obtained. The fry required by the Windu Kencana group under this programme has been provided by PT Permata Hijau and BBAP Jepara while feed are provided by PT President Feed and Golden Horse (PT Laut Tambak Subur).
Iin S. Djunaidah, Kasnadi, Yahya and Sugianto, Brackishwater Aquaculture Development Centre, Jepara, Central Java, Indonesia

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05
Dec

SHRIMP CULTURE TECHNOLOGY LEVEL

Aside from having two culture systems based on species stocked, that is shrimp monoculture or shrimp/milkfish polyculture, there are three levels of shrimp culture technology as mentioned earlier. The three levels may be more clearly defined as follows:

  1. Low level or traditional
  2. Medium level or semi-intensive; and
  3. Advanced level or intensive.

Each level has its own characteristics and are discussed below.

1. Low Level Shrimp Culture
Traditional shrimp culture operation uses very low level technology in which the ponds are not systematically designed and laid out and use only one sluice gate to both supply and drain water. The pond bottom is provided with canals which could be from 16% to 20% of the relatively large pond areas.

The tambak farmers prepare the pond by merely drying and scooping mud out of the pond bottom canal which is plastered on the dike. The sluice gate is repaired to some extent and filters consisting of bamboo screens are installed.

Shrimp fry usually comes from the wild and are merely allowed to enter with the tide. Usually these are mixed with fry of other species including fish, with the amount of fry entering beyond the farmers’ control. This can be done several times so that there is really no way of knowing the actual number coming in.

The shrimps are harvested using a bamboo-screen barrier trap or more often by the use of a posongan or trap set at the mouth of the sluice gate. A bag net may also be set at the sluice gate itself and lighted with a kerosene lamp at night. Often large lift nets may also be used. The culture period is not set because the size of the shrimp fry coming in is not uniform. The harvest is low and ranges only from 300 to 800 kg/ha per year.

The government is trying to improve the production level in these traditional ponds by encouraging pond improvements and the controlled stocking even at a low density of 15,000 to 20,000 fry/ha/crop. This may also be done in polyculture with milkfish and at the same time take advantage of existing natural food which generally is abundant.

2. Medium Level Shrimp Culture
The pond compartments in a medium level tambak are generally already constructed following a proper lay-out and are no longer as wide as traditional ponds. Usually, peripheral pond bottom canals are still provided and cover about 32% to 40% of the tambak area. Each pond is already provided with 2 sluice gates, one for supply and another for drainage so that the dirty water from the pond does not get mixed up with the clean water. The water generally is deeper than that of traditional ponds and can be maintained at 100 cm. Pond preparation consists of drying of the pond bottom, and fertilization with organic and inorganic at the required level in order to stimulate the growth of natural food. Pond pest control is practiced with the use of pesticides in order to eliminate predators and competitors.

Shrimps are stocked at a set density using either natural fry or hatchery fry although natural fry are often very variable in sizes since they do not necessarily come from one spawning unlike hatchery fry. The stocking density is about 10 fry/m2 and the culture period about 120 days. The harvest can reach up to 1,500 kg/ha/year.

Just like traditional tambak, semi-intensive tambak may also practice polyculture of shrimps with milkfish so that the natural food can be fully utilized and over-all production is increased. The government is also recommending the improvement of semi-intensive culture in order to increase their production through the INTAM programme.

3. Advanced Shrimp Culture Practice
Advanced shrimp culture tambaks have very well designed ponds which are already almost ideal and have separate supply and drain gates. However many also use PVC pipes instead of sluice gates for bringing in new water using pumps as well as for draining. With this method each pond compartment can be filled or drained at any time, meaning the water can already be managed properly. The ponds are also relatively small for easier control.

The ponds are prepared according to standard practices, which include complete drying of pond bottom, liming to control soil pH and pesticide application to eliminate predators and competitors. In addition, the water quality is maintained in good condition with the use of paddlewheels or other aeration system and with the use of certain chemicals.

The fry used in intensive ponds come from the hatchery and are stocked at a density of 50 fry/m2 or higher. In this type of culture, fertilization is no longer practiced since it relies completely on artificial feed. Culture duration is 120 days. Harvest is done on a total basis by draining the ponds and reaches about 3,000 kg/ha per crop or more. In intensive culture, polyculture with milkfish is no longer practiced.

Reserch by Bambang S. Ranoemihardjo,Brackishwater Aquaculture Development Centre, Jepara, Central Java, Indonesia

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05
Dec

SOME CONSIDERATION IN SHRIMP CULTURE OPERATION IN INDONESIA TAMBAKS

Three levels of shrimp culture are identified, namely: 1) low-level or traditional, 2) medium-level or semi-intensive and 3) advance-level or intensive. Their relative merits and demerits are discussed. While traditional shrimp culture requires low capitalization and operating cost and produces large shrimps which commands high prices, its total production is low and management and control is difficult.

Meanwhile advance or intensive shrimp culture may be able to produce at very high level but the shrimps produced are relatively small while the capitalization and operating costs are very high. It appears that with the present low shrimp price situation, the best approach is the medium level or semi-intensive culture because the operational costs is not as high as for intensive culture while the shrimps at harvest are fairly large and commands a high price.

At present many tambak operators already understand and have experience in the culture of black tiger shrimps (P. monodon) in tambaks. Actually not only tambak operators have ventured into rehabilitating old ponds or developing new ones for shrimp culture, but even small and large entrepreneurs from other business activities, have jumped into such ventures. Ever since the government started to consider shrimp as a prime nonoil export commodity from the fisheries subsector, shrimp culture progressed rapidly. This was also one way for the government to prevent the displacement of many people dependent on shrimps after the Presidential Decree banning trawl fisheries was implemented in 1980, and at the same time direct the shrimp production activity from capture to culture. The impact of this is the increase in the area developed for tambak as can be seen in the statistical data. It is hoped that the government shall continue to push for increased production through aquaculture in a manner which shall be environmentally sound.

In the beginning shrimp was only a side-product in tambaks, this became a primary product only in the mid-1980′s when shrimp culture expanded rapidly. In order to stimulate and increase shrimp production the government, among others, launched the INTAM programme which is more or less based on the success of similar schemes for other agricultural commodity such as rice.

INTAM programme involves intensification in existing tambaks. In principle tambak intensification is to be carried out by applying the Sapta Usaha Pertambakan, which consists of the following:

  1. Tambak rehabilitation/improvement
  2. Water supply and management
  3. Pond bottom preparation
  4. Stocking with good quality fry and feeding
  5. Pest and disease control
  6. Harvest and marketing
  7. Operations management

The extent of application of Sapta Usaha Pertambakan depends very much on the level of tambak culture technology which is known to consist of three levels namely low, medium and advanced level.

Bambang S. Ranoemihardjo, Brackishwater Aquaculture Development Centre, Jepara, Central Java, Indonesia

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05
Dec

HATCHERY OPERATION IN EAST JAVA, INDONESIA

In East Java, of the 55 hatcheries presently registered for development, 29 commercial hatcheries (PPUW and Subcentre, East Java not included) are in full operation as of May 1989. The PL production capacity of the hatcheries vary between 10 and 100 million per annum. Hatchery operation technology in the region differs from one hatchery to another. This is mainly due to the locality, topography, environmental condition, availability of fund and the technology used by the consultant or the technician concerned.

Distinct categorization is possible in some of the hatcheries, i.e., “Taiwan” or “Hawaii” as claimed while some, especially those run by locally trained technicians, defy definite classification, since they could be using elements from different systems depending upon the experience or biases of the technician in charge. A summary of basic facilities and hatchery management technology of the systems are given in.
Hawaii System
The hatchery operation system which is locally known as Hawaii, evolved from the technology introduced by the Indonesian Government’s ADB-assisted Brackishwater Aquaculture Development Project, No. 1 Hatchery in Situbondo, East Java. The hatchery was set up and started by the Hawaii-based consulting company, Aquatic Farms Ltd. (AFL). The hatchery was inaugurated on May 1987. During the first year of operation it is reported to have exceeded its production target of 40 million shrimp fry by 5 million.
One distinct feature is that the rectangular larval tanks have V- bottoms. The original AFL-designed hatchery used fiberglass larval tanks. Later hatcheries following the AFL design shifted to the much cheaper concrete tanks but still following the same shape. Broodstock are maintained in separate tanks in total darkness with special feed. Small fiberglass tanks are used for spawning. After spawning, the eggs are collected, disinfected and transferred to 25-liter tubular hatching jar with conical bottoms made either of plastic bags or fibreglass. Intense artificial light and strong aeration is provided during the hatching process.

Upon hatching the nauplii are then transferred to the larval rearing tanks. Normally the nauplii stocking density is between 100 and 150 nauplii per litre. In the larval tanks aeration is provided from pipes laid at the V-shaped bottom along the length of the tank. The tanks are covered with canvas through out the rearing period. Upon reaching PL-1 to PL-5 the postlarvae are then transferred to larger postlarval rearing tanks. The tanks are made of concrete with flat bottom. The postlarvae are reared until PL-20, at which stage it is ready for sale. A production of between 10 and 40 postlarvae per litre is achieved with this system.

The water utilized is sand-filtered and treated with chemicals such as NaOCl (5–10 ppm) and EDTA (4–8 ppm). Daily percentage exchange of water for larvae (zoea to mysis) in the larval rearing tank is low (20–30%) and for postlarvae percentage of water exchange is increased to between 40 and 70%. Salinity of above 30 ppt is maintained for the larval rearing water. The temperature of water is kept at between 30 and 32 degree centigrade without the use of heaters. The system relies on a large reservoir (150–400 mt). Each hatchery has at least two reservoirs. For prophylaxis, different chemicals are used, such as chloramphenicol (3–4 ppm); Furazolidone (1–2 ppm); Treflan (0.05 ppm); Malachite-green (0.01–0.1 ppm); formalin (10–25 ppm).

For artificial feed, commercially prepared products from Japan, USA and Taiwan are used both for larvae and postlarvae. However, for broodstock and spawners, feed such as crab, mussel or squid meat are used. Artemia nauplii are given from mysis through PL.

According to the technicians, in some cases the nauplii are weakened or killed with warm water before feeding. The Artemia cysts are rarely decapsulated.

Micro-algal food consists only of the diatoms, Skeletonema sp. and Chaetoceros sp. The BADP hatchery has a laboratory with good facilities for isolation, pure culture maintainance, and scaleup. However, the technicians take advantage of the natural occurrence of an almost pure culture of Skeletonema sp. at Tanjung Perak, Surabaya harbor by using this natural stock as starter for mass culture. Algal cell count is controlled in feeding. At present some hatcheries are trying the microflagellate, Tetraselmis sp. provided by the East Java shrimp culture development subcentre.

Taiwan System
The Taiwan hatchery operation technology was introduced by Taiwanese technicians who were brought in by private enterprises to plan, implement and operate on their behalf. The development of the Taiwan system has been recent (1987) and a few hatcheries are still in the implementation stage in the region.

The system utilizes large larval and postlarval rearing tanks (20–60 mt). The facilities and operation technology of the system is simple. The rearing tanks (broodstock, spawning, larval and postlarval) are almost of the same size and design. The size depends on the production capacity of the hatchery. The tanks are usually square or slightly rectangular with a depth of between 1.2 and 1.8 meter. From spawning to larval rearing up to postlarvae the same tank is utilized. Stocking density of nauplii is not determined, but the emphasis is on the number of spawners used. The number of spawners used depends on the technician.

The aeration for the tanks are provided by plastic hoses hanging from the top of tanks supported by ropes or wires secured across the tank. The tanks are covered with canvas during the nauplii to early PL stage. But at a later postlarval stage (PL) the tanks are uncovered. The postlarvae are reared until about PL-20. Normally a 40 cubic meter capacity rearing tank can produce as much as 3.0 million of PL-20 fry. In some hatcheries the PL-20 are nursed in large (75–100 mt) nursery tanks (shallow with sandy bottom) before selling or stocking in ponds.

The water utilized is sand-filtered but is not chlorinated. However, in some hatcheries, the filtered seawater is passed through activated carbon or FeO. The filters are always overhead and the filtered water are stored in a small (48–75 mt) over head tank. A hatchery would have at least two sets of such filter and reservoir. Larval rearing water is seldom changed. But according to technicians a small percentage (5–10%) of water is change daily. High salinity (above 30 ppt) water is used for larval rearing. Most of the hatcheries use heaters to maintain a high temperature of up to 34.0°C. Various powders are used during the larval rearing process but the exact nature cannot be determined and the Taiwanese technicians are often secretive or unable to communicate in Indonesian or English. These powders are believed to be different types of antibiotics.

Commercially prepared feeds from Taiwan are mainly used as artificial feed for larvae and postlarvae. Artemia nauplii is also essential as feed for mysis through postlarvae. However during the early larval stage from zoea through mysis, Skeletonema is used. The success of the Taiwan system in East Java is largely due to the presence of naturally dominant (over 90%) Skeletonema sp. at Tanjung Perak, Surabaya. The situation is similar to that of Kaoshiung Habour in Taiwan (Liao, et al, 1983). The Skeletonema sp. stock is routinely collected from the area by plankton net and transported to the hatchery for mass culture. The amount of algae given appears to be in excess. A laboratory for maintaining pure algal stock or scale-up culture is not provided in the Taiwan hatcheries.

Mixed System
Many of the hatcheries, especially those run by locally trained technicians mainly at BBAP Jepara, cannot be categorized under either system. Before the coming of the Taiwanese technicians, the only technology available was that from BBAP Jepara. This was introduced through the UPPUW in Pasir Putih, Situbondo District. With the recent introduction of the Hawaii and Taiwan systems, the hatchery technicians in the region modified their practice and tried to apply what each felt was the best of either systems.

Generally, the mixed system uses the same procedure in the management of broodstock through spawning to larvae and postlarvae rearing as the Taiwan system. Chemicals and antibiotics are routinely used in water management and disease control. The rearing tanks are bigger than those of the Hawaii system but smaller than those of the Taiwan system. A laboratory is maintained to monitor the water and larval conditions. For feed the system also relies on commercially prepared feeds and Artemia nauplii. Algal feed consist of Skeletonema sp. with starter stock routinely collected from Tanjung Perak for mass culture. A few hatcheries have a laboratory for scale-up culture and for maintaining pure algal stock.

Unlike the Hawaii system which relies on large water reservoirs, these hatcheries have small or medium size water reservoirs. At times some of the larval tanks are used as water reservoirs. The stocking density of nauplii is slightly more (100–200 N/litre) and the production is at times higher (10–50 N/litre) than the Hawaii but lower than the Taiwan system. Compared to Hawaii system there appears to be a higher risk involved most probably due to the instability of the technique. In some cases, some hatcheries operate both systems (Hawaii and Taiwan) using the same facilities at different times, with different technician.

NYAN TAW. FAO-UNDP INS/85/009 Shrimp Culture Development Project, Jepara, Central Java.

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05
Dec

SHRIMP HATCHERY TECHNOLOGY IN EAST JAVA, INDONESIA

In East Java, there are at present 55 shrimp hatcheries registered for development of which 29 commercial hatcheries are in full operation. The production capacity of these hatcheries ranges from 10 to 100 million PL’s per annum. Locally, these hatcheries are categorized either as “Hawaii” or “Taiwan” system.

The distinct difference is that those categorized as “Hawaii” use ambient temperature and clear water (maintained by high exchange rate) while the latter maintains a high temperature (up to 35°C) with the use of heaters while the water is allowed to become rather murky (due to very little or no water exchange).

Those hatcheries that from the very start were intended to operate using the Hawaii system tend to be well engineered and are characterized by having a large reservoir. Those using the Taiwan system might have a central heating system either using steam from oil-fired boilers or electric immersion heaters.

Some hatcheries might have started using Taiwan system only later to convert to Hawaii system operationally without revising the basic design. Others may use elements of both depending on the technicians’ biases. All use an array of antibiotics for prophylaxis and various artificial larval feed in addition to diatoms (mainly Skeletonema) and brine shrimp.

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